Bis-(2,3-dihalopropyl) chlorophosphonate



Patented May 11, 1954 UNITED STATES PATENT OFFICE BIS-(2,3-DIHALOPROPYL) CHLORO- PHO SPHONAT'E No Drawing. Originalapplication May 18, 1950,

Divided and this application February 23, 1951, Serial No. 212,526

3 Claims. (Cl. 260461) Serial N; 162,824.

This invention relates to cellulose derivatives and relates moreparticularly to certain novel organic derivatives of cellulose, whichare highly resistant to burning.

This application is'a division of our copending application S. No.162,824, filed May 18, 1950.

An object of this invention is the provision of flameproofing agentscomprising certain novel I haloalkylhalophosphonates which are adaptedto be reacted with cellulose derivative materials having free hydroxygroups to render the same fiameproof.

Other objects of this invention will appear from the following detaileddescription.

Organic derivatives of cellulose materials are thermoplastic and, whenheated to an elevated temperature, may be softened sufficiently to causethem to flow. Since organic derivatives of cellulose materials are alsoflammable, the heat generated when said organic derivatives of cellulosematerials are ignited results in a melting of the burning material andthe resulting dripping of burning fragments of molten material greatlyincreases the fire hazard involved. Numerous proposals have been madefor treating organic derivatives of cellulose materials with the objectof rendering said organic derivatives of cellulose textile materialsnon-flammable. The suggested treatments usually involve the applicationof chemical agents such as ammonium compounds, for example, to theorganic derivatives of cellulose materials. While the presence of thesecompounds on the organic derivatives of cellulose materials does reducetheir flammability and their tendency to melt and drip when burning, theammonium compounds as well as other types of compounds usually employedfor such fiameproofing treatments impart a somewhat stiif and harsh handto the treated materials. Such a change in the hand of the treatedmaterials is quite undesirable. Furthermore, the protective actionachieved by such treatment is usually destroyed quite readily by eitherwashing or dry-cleaning.

We have now found that organic derivatives of cellulose materialscontaining free hydroxyl groups may be rendered completely and perma-\nently non-flammable by reacting the same with a haloalkyl ester ofhalophosphoric acid. An esterification reaction takes place resulting inthe formation of a further ester linkage between the haloalkyl phosphateester and the free hydroxy group or groups present in the cellulosederivative. Hydrogen chloride is split 01f as a by-product and theproduct obtained is a haloalkyl-phosphoric acid ester of the cellulosederivative employed. Since the secondary ester linkage formed betweenthe phosphoric acid and the free hydroxy groups of the cellulosederivative is a chemical bond, neither washing nor drycleaning solventshave any harmful efifect whatever on the protective action resultingfrom the esterification reaction. The actionis permanent and is far moreeffective with the use of less material than in the case of materialsapplied merely to the surface.

The novel flameproofing agents of our invention have the followinggeneral formula (X),,-alkyl0 P=O (X),.alkylO where n is a whole numberand at least 2 and X is selected from the group consisting of chlorineand bromine.

As examples of the novel haloalkyl-halophosphonates which may beemployed for modifying said organic derivative of cellulose materials byreaction therewith to render the same non-flammable, there may bementioned bis-(2,3-dichlorpropyl)-chloro-phosphonate andbis-(2,3-dibrom-propyl) -chloro-phosphonate.

The improved flame-proofing agents of our invention may be obtained byreacting phosphorus trichloride with an alkylene oxide, a halo-' genatedaliphatic alcohol or a halogenated alkylene oxide and then chlorinatingor brominating the haloalkyl phosphoric acid ester to convert the sameto the corresponding phosphoric acid ester chloride or bromide. Thus,phosphorus trichloride may be reacted with 2,3-dibrompropanol-l or2,3-dichlorpropanol-1, for example, to form the corresponding triesterof phosphorus acid. Upon chlorination, the phosphorus acid triester thusobtained is converted to the bischloralkyl ester of chlorphosphoricacid.

In order further to illustrate our invention but without being limitedthereto, the following examples are given:

Example I 774 parts by weight of 2,3-dichloropropanol-1 are placed in areaction vessel and 137 parts by weight of phosphorus trichloride areslowly added with stirring while maintaining the temperature constant atabout 35 C. After standing for about 30 minutes, nitrogen gas is bubbledthrough the reaction mixture to remove any hydrogen chloride, and theproduct then distilled over barium carbonate under a pressure of about 5mm. absolute. The fraction of the crude mixture which nitrogen throughthe reaction mixture while maintaining the same under vacuum.

The product, comprising bis-(2,3-dichlorpropyl) -chlorophosphonate, maythen be reacted with a cellulose derivative having free hydroxy groupsto impart the desired non-flammable properties thereto.

Example II 109 parts by weight of 2,3-dibrompropanol-l.

are placed in a reaction vessel and 22' parts by weight of phosphorustrichloride are slowly added with stirring whilemaintaining thetemperature constant at about 10 C. After stirring for about 30'minuteschlorine gas is bubbled under the liquid surface with stirring andapplication of vacuum. This chlorination requires 30 minutes with thetemperature maintained at 20 C. After'addition of 200 parts by Weight ofbenzene, hydrochloric acid gas is removed, together with benzene, bystirring and warming to 40 C. and application of vacuum which isgradually increased, over a period of about 3 hours, to about-2 mm.pressure.

The product, comprising bis-(2,3-dibrompropyl) chlorophosphonate anddibrompropyl chloride, may then be reacted with a cellulose derivativehaving free hydroxyl groups to impart the desired non-flammableproperties thereto. The dibrompropyl chloride may be removed duringisolation of the final cellulosic reaction product.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by LettersPatent is:

1. A phosphonate of the group consisting of bis-(2,3dichlorpropyl)-chlorophosphonate and bis-(2,3 dibrompropyl)-chlorophosphonate.

2. Bis- (2,3-dichlorpropyl) -chlorophosphonate.

3. Bis- (2,3-dibrompropyl) -chlorophosphonate.

References Cited in the file Of this patent UNITED STATES PATENTS NameDate Lommel Nov. 28, 1933 OTHER REFERENCES Number

1. A PHOSPHONATE OF THE GROUP CONSISTING OFBIS-(2,3-DICHLORPROPYL)-CHLOROPHOSPHONATE ANDBIS-(2,3-DIBROMPROPYL)-CHLOROPHOSPHONATE.